alpha-naphthylmethyl esters of hydroxy-aliphatic acids



Patented Aug. 28, 1945 PAT T FICE a-NAPHTHYLMETHYL .Es'rERs ornit- DROXY-ALIPHA-IID noms ,7

Jack .T hurston, Cos Cob; -*Gonn., andJohn Grim, New York, N. Y., assignnrsttnlAmeri'can Cyanamid Company, New ltoi k, Y., a:cnrp.o-

ration of Maine No Drawing. k pplicationflccember 22, 1941,

Serial No. 424,058

4 Claims.

This invention. relates to a-naphthylmethyl esters of dhydroxy-alipha-tic acids, and to cellulose derivatives plasticized therewith. k

We .have .discovered that the a-naphthylmethyl esters of a-hydroxy aliphatic acids such as a-hydroxyisobutyric, lactic, malic, tartaric, and citric acids may be prepared by esterifying a-naphthylcarbinol with the desired hydroxy .acid 'or by causing an a-naphthylmethyl halide and a salt of the desired hydroxy .acid to react.

Thesnew'esters of the present invention "have very low vapor pressures and are not attacked .by water. Moreover, we :have found that they make excellent plasticizers for most cellulose derivatives. It is ,well known that cellulosic compositions such as cellulose esters and ethers, which are commonly used in the preparation of lacquers, molding compositions, photographic films, and the like 'are characterized bythe fact that in the dry state they are excessively hard j and brittle and upon subjection "to relatively slight fiexure or "extension theyhhedkandbreak. For purposes :of overcoming this fle'fect it has been customary to incorporate in ecellulosic lacq-uers or varnishes a substantial portion-of a plasticizing agent. These plasticizers impart elasrticityand ductilityto the dried lacquer or varnish :film obtained on evaporation of. the volatile .solvent. .In this manner, cracking or peeling-of the film .may be avoided audits adhesivesqualitie's .of plasticizers into cellulosic molding composi- .tions .bring about .a more rapid andeven :flow oi the materials and molding operations may be conducted at much lower temperatures than when no plasticizer is present. I

The plasticizing esters of thepresent invention are for .the most part --compatilole with andthereiore-mayhecompounde'd, eitheralone or together with other softening agents as camphor, dibutyl phthalate, etc., with inorganic acid esters of cellulose such as cellulose nitrate; with single organic esters of cellulose such as celluloseacetate, cellulose propionate, cellulose butyrate and cellulosewstearate; swithrmixed organic acid :esters of :oellulose :such as cellulose acetate-stearate, cellulose :acetate-propionate, cellulose acetate i-butyrate, :cellulose acetate-lactate, .and cellulose :acetate tartratez; with mixed inorganic and organic acid esters of cellulose :such :as cellulose nitroace'tate; and cellulose others such as ethyl cellulose and *benzyl cellulose.

The invention will be described in greater-"dc tail in conjunction with therollowing specific examples inwhich they proportions are given in parts by weight. 'lEt should be understood that these examples are merely illustrative and are notiintended to limit the scope of the *inverition.

'ExAMrnE *1 v a-Waphtmilmethz l u hgdrowyisobw'tymte' I use parts 1 (ch10romethyld' nafihthalene,T1656 parts uhydrcxyisobutyric acid "and-4 7.3 parts On cool-ing a yellow o' ily layer separated, which improved. Inoorporationrof substantial portions crys'tailiZeZl When coolecI tn'an ice-salt bath. The solid waadistiil'ed at 1 2'B'- 1 33 15.. at about "1 prtsurefyielding 5l3 grams ewd-"5% of the theo retical yield o i a'viscous and light straw colored product crystallized "on standing -overnight. After recrystallization irom heptarre fiche a naphthylmethyl ruhydroxyisdbutyrate' melted at 50-52 C. and 'iha'd a saporfification number of a-Na.phthyl1mzthyl malate 134 'parts (1.0 mol) malic acid, 395 parts (2.5

n rdls) u naphthydcarbmdl, 161R) 'p'arits xylene and -2.5 parts sodium hydroxide were re'fitnred "forff5 hours in a 3 ne'cked iiaskfitted with --atstirrer and water trap. During this time'ftllih ace. of .water -'were distilled. ll he :sI-ightly d1oudy-"so lution was filtered, washed several times-with sodium abicanhmate solution, washed with water, dried anhydrous sodium sulfate, and tlren decolorized with charcoal. The solvent-"was rea-Ncphthylpz ethyl lactate 104 parts 1.5 mols) 85% lactic acid, 158 parts (1.0 mol) u-naphthylcarbinol, and 650 parts xylene were refluxed in a 3-necked flask fitted with a stirrer and a water trap for 6. hours, dulf'.

ing which time 52.5 cc. of water were removed. The xylene solution was washed several, times with dilute sodium bicarbonate solution, washed with water, dried with sodiumsulfate and finally decolorized with charcoal. After. filtering, the

EXAMPLE 7 A. Compatibility Mixtures containing varying proportion of a-naphthylmethyl u-hydroxyisobutyrate and solutions of cellulose derivatives were poured onto glass and the films examined immediately after drying. A will be evident from the following table, the isobutyrate was found to be compatible with each of the cellulose derivatives investigated. The symbol denotes complete miscibility of ,sc -naphthylmethyl u-hyroxyisobutyrate with the cellulose derivative in question.

solvent was removed by evaporation at reduced pressure and the temperature of the ester was raised to 150 C. in order to remove the last traces of solvent. p The u-naphthylmethyl lactate obtainedwas a light brown viscous syrup with an acid number of 1.0-. a

EXAMPLE 4 4 s a-Naphthylmethyl ta rtrote .150 parts (1.0 .mol) tartaric acid and 395 parts (2.5 mols) u-naphthylcarbinol were heated in a 3-necked flask providedwith a stirrer for 1 hour at 170 C. At the end of this time water of esterification was no longer being evolved. The. reaction mixture was then dissolved in ether, neutralized with I dilute sodium bicarbonate solution, washed with water, dried with sodium sulfate and decolorized with characoal. After the ether was evaporated, the a-naphthylmethyl-tartrate crystallized. The crystalline ester was found to have ameltingpoint of 95 -100" C. andan acid number of1.0.... I

. EXAMPLE 5 l s-Napltthylmethyl citrate;

a-naphthylcarbinol and 2500 parts of kerosene boiling at 200 C. contained in a 3-n'ecked flask fitted with a stirrer and water trap were refluxed until 72 cc, of water were distilled. The kerosene was then removed at reduced pressure and the residuedissolved in ether and purified as described in the-preceding examples. p

The brown resinous a-naphthylmethyl citrate obtained had an acid number of 3.0.

The esters prepared as described in the above examples were tested for their plasticizing efiects on cellulose derivatives.

EXAMPLE 6 25% and 50% concentrations of u-naphthylmethyl a-hydroxyisobutyrate weremixed with a 20% solution of nitrocellulose in a solvent comprising by volume .4 parts toluene, 3 parts ethyl acetate, .2 parts butyl acetate and 1 part butyl alcohol and the mixtures poured onto a glass plate to dry. The resulting films were found to be well plasticized and. they possessed considerable strength. l

Isobutyratecellulose derivative Cellulose derivative Nitrocellulose20% solution is lacquer solvent, :comprising, by volume, 4 parts toluene, 3 1 partscthyl acetate, 2 parts butyl acetate and 1 part butyl alcohol oo 00 oo Ethyl cellulose20% solution in :20 toluene:

ethyl alcohol, by weight co oo o Cellulose acctate20% solution in :10 acetone:

ethyl alcohol, by weight; 00 00 0o Cellulose nitroacctntel5% solution in acetone 0 w Cellulose acetobutyrate-l5%' solution in methyl ethyl ketone oo 00 o Cellulose ocetopropionatc-20% solution in methyl ethyl ketone o 00 Benzyleellulose. 20% solution in ethyl acetate 0o O0 in B. Tensile strength Tensile strengths of mixtures Of amaphthylmethyl a-hydroxyisob-utyrate and nitrocellulose in the proportions of 1:9 and 5:5 were compared with those'o-f mixtures of camphor and nitrocellulose in the same proportions with the following results:

, Film Film Tensile Elongawidth thickness strength tion a Nnphthylmethyl a-hy- Inches Inches Lbsn/in. Per cent droxyisobutyrate and nitrocellulose-l:9-. l 0.5 0.001 11,000 4 Camphor I and nitrocellulose-1:9 0. 5 0.001 11,200 5 a-Naphthylmethyl a-hydroxyisobutyrate and nitrocellulose-5z5 0. 5 0.0015 3, 730 20 Osmphor and nitrocellulose-5:5 0. 5 O. 0015 5, 740 3 It. will be apparent from the above data that or naphthylmethyl a hydroxyisob-utyrate and camphor are verysirnilar in their plasticizing effects in films containing the 1:9 mixtures. The

5:5 a-naphthylmethyl a-hydroxyisobutyrate-nitrate, benzyl cellulose and ethyl cellulose were prepared. a-Naphthylmethyl esters of lactic,

.malic, and tartaric, acids were then dissolved in equal weights of acetone and various combinations of the two types of solutions were prepared by thorough mixing, The mixtures were flowed outon glass and allowed to air dry overnight after which the film was removed from the glass. The following data were obtained:

Plasticizing action of hydrozcy esters of a-naphthylcarbtnol above, in the preparation of lacquers, varnishes, molding compositions, photographic film, artia-Naphthylmethyl esters of-- ggggigs Solvents, parts Lactic Malic Tertaric Acetate 80 acetone, 20 ethyl acct 33% *2 good plesticizerfln .Q Nitrate 80 acetone, 20 ethanol enzyl 50 toluene 33%,;tacky, 15%: very good plas- 33;Z,z tacky, 15%: very good plasiclzer. lOlZel'. Ethyl 80 toluene, 20 ethanol 33%:too soft; 15%: very good [1188- 33%: well plasticized.

ticizer.

1 Concentration of ester in the dried film.

ficial silk, coating composition, laminated articles, etc.

What we claim is:

1. The a-naphthylmethyl ester of a whydroxy aliphatic carboxylic acid.

2. The a-naphthylmethyl ester of a a-hYdI'OXY aliphatic monobasic carboxylic acid.

3; The u-naphthylmethyl ester of a-hydroxyisobutyric acid.

4. The a-naphthylmethyl ester of lactic acid. JACK T. THURSTON. JOHN M. GRIM. 

